What is a TOPOJSON file?

A TopoJSON file format is a geoJSON format extension that encodes geospatial topology. TopoJSON files contain both attribute data and geospatial data (arcs). Arcs — or sequences of points which can then be used to define line strings and polygons — can be referenced numerous times by different shapes within the file, and therefore greatly decrease data redundancy and the overall size of TopoJSON files. This format's use of arcs set the TopoJSON apart from other GIS formats. This format is often used by software such as Microsoft PowerBI.

Specifications

A complete TopoJSON dataset contains the following specifications when exporting from Spotzi:

• The first section contains the arcs, as well as other information necessary for plotting the TopoJSON data on the map;
• The second section includes information pertaining to the file's geometry;
• The last section includes more information about the attribute.

Associated filename extensions

• .geojson
• .topojson
• .json